One widespread method of storing forage crops is to package them in large cylindrical bales. Much of the appeal of this practice comes from the bales' inherent ability to shed rainfall and other elements. Contrary to widely held perceptions however, losses due to weather exposure on round bales are quite high. In research trials carried out in the eastern United States, large round bales stored outside without protection for six months or more were commonly found to experience dry matter losses of 30 percent or greater.
Numerous solutions to reduce these storage losses have been proposed, with various degrees of success. These solutions include wrapping the circumference of a bale with twine or plastic net or film material, covering the top of the bale with plastic “caps”, or the complete envelopment of the bale in plastic film. None of these methods work to reliably prevent crop loss in dry hay baling, but the complete envelopment process has shown to be successful in baling high moisture hay or silage.
Concerning crop loss in dry hay baling, absorption of rainfall and/or wicking of soil moisture creates most losses due to spoilage, mold, etc. Losses from complete or circumferential solid film wrapping results from internal moisture trying to escape from the relatively dry hay, then condensing as it hits the plastic. This condensed moisture results in exterior portions of the bale remaining damp for extended periods of time, causing spoilage in these outer layers. Such spoilage has been shown to be similar to unprotected bales in some studies.
The problem to be solved then is to provide a protective covering for a bale which effectively prevents crop loss from the environment while being cost effective.